Pool closing · Texas
When to Close Your Pool in Lewisville, TX: Deadline, Window & Checklist
Last updated: July 15, 2026 · Model window year: 2026 · dates · checklist · FAQ
Target November 9 as the practical closing deadline in Lewisville. Our model of NOAA 1991–2020 normals keeps the 7-day mean above 61°F until October 30; after that, cooling water winds algae down while you work the checklist below. The hard stop is equipment freeze damage — normals put Lewisville's first 32°F night near November 17.
Lewisville closing dates at a glance
| Closing window | October 30 – November 9 |
|---|---|
| Close by (deadline) | November 9 |
| First freeze, 50% probability | November 17 |
| Open by (recommended) | March 18 |
| Opening window | March 11 – April 1 |
| 61°F crossing (7-day mean) | April 1 |
| Swim-season length (80°F+ days) | 157 days |
| NOAA normals station | Grapevine Dam · 7.8 mi · 585 ft |
A classic four-season pool calendar: open early into cold water, close late into cold water, and Lewisville's 157 days of prime swimming sit safely in between.
The same model in water terms: Lewisville's estimated pool temperature runs about 63°F in mid-April, 80°F in mid-June, 86°F in mid-August, and 70°F in mid-October, peaking near 86°F. Those four checkpoints — not any calendar holiday — are what the windows above are protecting.
The 12-step Lewisville winterizing checklist
A closing is a plumbing project with a chemistry warm-up. Start a few days ahead of your target date, keep every dose per its product label, and don't skip the photographs — spring-you reassembles from them.
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Balance the water a few days ahead
Three or four days before closing, adjust alkalinity and pH into label ranges. Balanced water is gentler on the liner, plaster, and equipment through the long covered months ahead.
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Deep-clean the pool
Skim, brush walls and steps, and vacuum carefully. Any leaves or algae you seal under the cover become spring's chemistry problem, so closing day cleanliness pays twice.
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Service the filter one last time
Backwash sand or DE, or pull and rinse cartridges, per the manual. A filter stored dirty cakes over winter and starts spring half-clogged.
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Apply winter chemicals per label
Add a winterizing kit or your usual closing chemicals exactly as their labels direct for your volume, with the pump still circulating so everything distributes before shutdown.
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Lower the water level
Your cover's manual sets the number — commonly a few inches under the skimmer for solid covers, barely below normal for mesh. Stop there. The remaining water isn't laziness; it's ballast holding the shell in the ground.
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Blow out the lines and plug returns
Air through every line — skimmer, returns, cleaner — until each blows dry mist, plugging returns while the air still pushes. Nothing else on this list protects as much plumbing per minute.
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Protect the skimmer
Give the skimmer something cheap to break: a guard bottle or rated plug absorbs the ice expansion that would otherwise split the housing.
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Add pool antifreeze where blowouts fall short
If any line can't be verified dry, add pool-grade antifreeze per its label. Use only pool antifreeze — automotive products don't belong in pool plumbing.
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Drain the equipment
Open every drain plug on the pump, filter, heater, and chlorinator, and store the plugs in the pump basket so spring reassembly is a one-stop hunt. Move what you can indoors.
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Set the air pillow and cover
Center an inflated air pillow, then fit the cover and secure it with water bags, cable, or straps as designed. The pillow gives ice a place to push besides your walls.
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Calendar the off-season checks
Set a monthly reminder from November 9 to spring: check cover tension, pump off standing water, and glance at the water level. Fifteen minutes a month protects the whole closing job.
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Winterize the water features
Waterfalls, slides, and spillover spas hold water in places gravity won't clear — blow those lines separately and plug them, or they'll be the one crack you find in spring.
What to buy before the rush
Every item below sells out somewhere in Texas every October. Stocking the short list before the rush costs nothing extra and saves the mid-project store run — the chemicals guide explains what each category actually does.
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Expansion plugs + skimmer guard
Cheap rubber that stands between ice and your fittings.
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Pool antifreeze
For lines you can't verify dry — pool-grade only, per label.
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Winter closing kit
Closing chemistry in one box, dosed by pool volume.
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Air pillow
Gives ice somewhere to push besides your pool walls.
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Winter cover
Measure with overlap; the winter workhorse over everything else.
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Cover pump
Standing water is a cover killer; this is the counter.
How Lewisville compares locally
Two nearby data points to triangulate with: Carrollton, 6 miles from Lewisville, models its close at November 9 (the same day); Flower Mound, 8 miles out, at November 9. Lewisville's own window ends November 9. For the other half of the calendar see when to open in Lewisville, or scan the full year on the season page.
Every number on this page traces to one instrument cluster: Grapevine Dam, 7.8 miles southwest of Lewisville's center at an elevation near 585 feet. NOAA computed its 1991–2020 normals from roughly three decades of daily readings — long enough that one strange spring in Denton County barely moves the dates.
Field notes for Lewisville owners
Blowout first, antifreeze second
Air is the only guaranteed freeze protection: a line that's verifiably dry cannot burst. Antifreeze (pool-grade, per label) is the fallback for lines you can't confirm — long runs, low spots, water-feature plumbing. Doing antifreeze instead of a blowout, rather than in addition, is how most cracked returns happen.
Leaf season vs closing day
If your yard drops serious leaves, the cheap trick is a leaf net over the main cover through the drop, then one bulk removal before snow. Leaves that winter on (or worse, under) the cover steep like tea and hand you stained water and clogged pumps in spring.
Gas heaters get the manual, not a guess
Every heater brand sequences its winterizing differently — drain plugs, blower considerations, gas supply, control settings. The generic advice (drain fully, close the valve) is right but incomplete; ten minutes with your model's manual protects the most expensive component you'll winterize.
Lewisville pool closing FAQ
What temperature should water be to close a pool?
The practical target is water in the low 60s°F or below at closing day. Our Lewisville model has the sustained cool-down starting October 30; closing between then and November 9 means chemistry stays put and the spring reveal is a mild one.
Can you close a pool too early?
You can, and warm-water closings are why "we opened to a swamp" stories exist. The fix is patience: let Lewisville's water cool through the mid-60s°F — around October 30 by our model — then close inside the window that ends November 9.
Do I need antifreeze in pool lines?
It depends entirely on your confidence in the blowout. Lines that blew fully dry need nothing; anything uncertain — low runs, water features, a stubborn cleaner line — gets pool-grade antifreeze at the label's rate per foot. With Lewisville's freeze clock starting near November 17, uncertainty is the thing to eliminate.
How far should I drain my pool for winter?
As far as your cover manufacturer specifies and no farther — typically a few inches below the skimmer mouth for solid covers, near normal level for many mesh systems with skimmer plugs. Never drain fully: an empty shell can shift or crack under groundwater pressure.
What happens if you don't winterize a pool?
Expect equipment damage first — cracked pump volutes, split filter tanks, ruptured heater exchangers — then plumbing leaks that surface at startup. In Lewisville, normals put the first freeze near November 17; everything after that date is borrowed time for an unwinterized system.
When is the last safe date to close in Lewisville?
Our model's practical deadline is November 9 — set by the cool-down plus ten days (the freeze normal, November 17, leaves room to spare). Push much past it and you're winterizing in freeze-warning weather, rushing the blowout, and hoping the cover goes on before the first hard night. Inside the October 30–November 9 window, none of that drama applies.
Email me when Lewisville hits the closing window
Data: NOAA 1991–2020 climate normals via Grapevine Dam (7.8 mi); live outlook by Open-Meteo. Full attribution on the sources page. Model assumptions and error bars on methodology.